In downhole exploration and geologic resource recovery, the ability to obtain information about the conditions of the environment and the status of the equipment downhole can be helpful in making decisions. Optical frequency domain reflectometers (OFDR) are among the types of sensors used downhole. OFDR is an interferometer-based system that relies on the interference between signals generated or reflected by individual sources based on an optical signal. When the polarizations of the two signals are parallel to each other (0 degree angle between them), this provides maximum interference. However, when the two signals have orthogonal polarizations (90 degree angle between them), then there is no interference between the signals and, as a result, no signal from the interferometer. This results in noisy output from the OFDR system, which cannot know when the interferometer signal is null. Thus, an apparatus and method to ensure performance of the interferometer-based systems would be appreciated in the industry.